/*
 * Copyright (c) 2007-2012, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
package com.sun.org.apache.bcel.internal.classfile;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
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 *
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 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
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 *    "Apache BCEL" must not be used to endorse or promote products
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 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

import com.sun.org.apache.bcel.internal.Constants;
import java.io.*;

/**
 * This class represents a chunk of Java byte code contained in a
 * method. It is instantiated by the
 * <em>Attribute.readAttribute()</em> method. A <em>Code</em>
 * attribute contains informations about operand stack, local
 * variables, byte code and the exceptions handled within this
 * method.
 *
 * This attribute has attributes itself, namely <em>LineNumberTable</em> which
 * is used for debugging purposes and <em>LocalVariableTable</em> which
 * contains information about the local variables.
 *
 * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
 * @see     Attribute
 * @see     CodeException
 * @see     LineNumberTable
 * @see LocalVariableTable
 */
public final class Code extends Attribute {
    private int max_stack; // Maximum size of stack used by this method
    private int max_locals; // Number of local variables
    private int code_length; // Length of code in bytes
    private byte[] code; // Actual byte code

    private int exception_table_length;
    private CodeException[] exception_table; // Table of handled exceptions
    private int attributes_count; // Attributes of code: LineNumber
    private Attribute[] attributes; // or LocalVariable

    /**
     * Initialize from another object. Note that both objects use the same
     * references (shallow copy). Use copy() for a physical copy.
     */
    public Code(Code c) {
        this(c.getNameIndex(), c.getLength(), c.getMaxStack(), c.getMaxLocals(), c.getCode(), c.getExceptionTable(), c.getAttributes(), c.getConstantPool());
    }

    /**
     * @param name_index Index pointing to the name <em>Code</em>
     * @param length Content length in bytes
     * @param file Input stream
     * @param constant_pool Array of constants
     */
    Code(int name_index, int length, DataInputStream file, ConstantPool constant_pool) throws IOException {
        // Initialize with some default values which will be overwritten later
        this(name_index, length, file.readUnsignedShort(), file.readUnsignedShort(), (byte[]) null, (CodeException[]) null, (Attribute[]) null, constant_pool);

        code_length = file.readInt();
        code = new byte[code_length]; // Read byte code
        file.readFully(code);

        /* Read exception table that contains all regions where an exception
         * handler is active, i.e., a try { ... } catch() block.
         */
        exception_table_length = file.readUnsignedShort();
        exception_table = new CodeException[exception_table_length];

        for (int i = 0; i < exception_table_length; i++)
            exception_table[i] = new CodeException(file);

        /* Read all attributes, currently `LineNumberTable' and
         * `LocalVariableTable'
         */
        attributes_count = file.readUnsignedShort();
        attributes = new Attribute[attributes_count];
        for (int i = 0; i < attributes_count; i++)
            attributes[i] = Attribute.readAttribute(file, constant_pool);

        /* Adjust length, because of setAttributes in this(), s.b.  length
         * is incorrect, because it didn't take the internal attributes
         * into account yet! Very subtle bug, fixed in 3.1.1.
         */
        this.length = length;
    }

    /**
     * @param name_index Index pointing to the name <em>Code</em>
     * @param length Content length in bytes
     * @param max_stack Maximum size of stack
     * @param max_locals Number of local variables
     * @param code Actual byte code
     * @param exception_table Table of handled exceptions
     * @param attributes Attributes of code: LineNumber or LocalVariable
     * @param constant_pool Array of constants
     */
    public Code(int name_index, int length, int max_stack, int max_locals, byte[] code, CodeException[] exception_table, Attribute[] attributes, ConstantPool constant_pool) {
        super(Constants.ATTR_CODE, name_index, length, constant_pool);

        this.max_stack = max_stack;
        this.max_locals = max_locals;

        setCode(code);
        setExceptionTable(exception_table);
        setAttributes(attributes); // Overwrites length!
    }

    /**
     * Called by objects that are traversing the nodes of the tree implicitely
     * defined by the contents of a Java class. I.e., the hierarchy of methods,
     * fields, attributes, etc. spawns a tree of objects.
     *
     * @param v Visitor object
     */
    public void accept(Visitor v) {
        v.visitCode(this);
    }

    /**
     * Dump code attribute to file stream in binary format.
     *
     * @param file Output file stream
     * @throws IOException
     */
    public final void dump(DataOutputStream file) throws IOException {
        super.dump(file);

        file.writeShort(max_stack);
        file.writeShort(max_locals);
        file.writeInt(code_length);
        file.write(code, 0, code_length);

        file.writeShort(exception_table_length);
        for (int i = 0; i < exception_table_length; i++)
            exception_table[i].dump(file);

        file.writeShort(attributes_count);
        for (int i = 0; i < attributes_count; i++)
            attributes[i].dump(file);
    }

    /**
     * @return Collection of code attributes.
     * @see Attribute
     */
    public final Attribute[] getAttributes() {
        return attributes;
    }

    /**
     * @return LineNumberTable of Code, if it has one
     */
    public LineNumberTable getLineNumberTable() {
        for (int i = 0; i < attributes_count; i++)
            if (attributes[i] instanceof LineNumberTable)
                return (LineNumberTable) attributes[i];

        return null;
    }

    /**
     * @return LocalVariableTable of Code, if it has one
     */
    public LocalVariableTable getLocalVariableTable() {
        for (int i = 0; i < attributes_count; i++)
            if (attributes[i] instanceof LocalVariableTable)
                return (LocalVariableTable) attributes[i];

        return null;
    }

    /**
     * @return Actual byte code of the method.
     */
    public final byte[] getCode() {
        return code;
    }

    /**
     * @return Table of handled exceptions.
     * @see CodeException
     */
    public final CodeException[] getExceptionTable() {
        return exception_table;
    }

    /**
     * @return Number of local variables.
     */
    public final int getMaxLocals() {
        return max_locals;
    }

    /**
     * @return Maximum size of stack used by this method.
     */

    public final int getMaxStack() {
        return max_stack;
    }

    /**
     * @return the internal length of this code attribute (minus the first 6 bytes)
     * and excluding all its attributes
     */
    private final int getInternalLength() {
        return 2 /*max_stack*/ + 2 /*max_locals*/ + 4 /*code length*/
        + code_length /*byte-code*/
        + 2 /*exception-table length*/
        + 8 * exception_table_length /* exception table */
        + 2 /* attributes count */;
    }

    /**
     * @return the full size of this code attribute, minus its first 6 bytes,
     * including the size of all its contained attributes
     */
    private final int calculateLength() {
        int len = 0;

        for (int i = 0; i < attributes_count; i++)
            len += attributes[i].length + 6 /*attribute header size*/;

        return len + getInternalLength();
    }

    /**
     * @param attributes.
     */
    public final void setAttributes(Attribute[] attributes) {
        this.attributes = attributes;
        attributes_count = (attributes == null) ? 0 : attributes.length;
        length = calculateLength(); // Adjust length
    }

    /**
     * @param code byte code
     */
    public final void setCode(byte[] code) {
        this.code = code;
        code_length = (code == null) ? 0 : code.length;
    }

    /**
     * @param exception_table exception table
     */
    public final void setExceptionTable(CodeException[] exception_table) {
        this.exception_table = exception_table;
        exception_table_length = (exception_table == null) ? 0 : exception_table.length;
    }

    /**
     * @param max_locals maximum number of local variables
     */
    public final void setMaxLocals(int max_locals) {
        this.max_locals = max_locals;
    }

    /**
     * @param max_stack maximum stack size
     */
    public final void setMaxStack(int max_stack) {
        this.max_stack = max_stack;
    }

    /**
     * @return String representation of code chunk.
     */
    public final String toString(boolean verbose) {
        StringBuffer buf;

        buf = new StringBuffer("Code(max_stack = " + max_stack + ", max_locals = " + max_locals + ", code_length = " + code_length + ")\n" + Utility.codeToString(code, constant_pool, 0, -1, verbose));

        if (exception_table_length > 0) {
            buf.append("\nException handler(s) = \n" + "From\tTo\tHandler\tType\n");

            for (int i = 0; i < exception_table_length; i++)
                buf.append(exception_table[i].toString(constant_pool, verbose) + "\n");
        }

        if (attributes_count > 0) {
            buf.append("\nAttribute(s) = \n");

            for (int i = 0; i < attributes_count; i++)
                buf.append(attributes[i].toString() + "\n");
        }

        return buf.toString();
    }

    /**
     * @return String representation of code chunk.
     */
    public final String toString() {
        return toString(true);
    }

    /**
     * @return deep copy of this attribute
     */
    public Attribute copy(ConstantPool constant_pool) {
        Code c = (Code) clone();
        c.code = (byte[]) code.clone();
        c.constant_pool = constant_pool;

        c.exception_table = new CodeException[exception_table_length];
        for (int i = 0; i < exception_table_length; i++)
            c.exception_table[i] = exception_table[i].copy();

        c.attributes = new Attribute[attributes_count];
        for (int i = 0; i < attributes_count; i++)
            c.attributes[i] = attributes[i].copy(constant_pool);

        return c;
    }
}
